1. Field of the Invention
The invention relates to a displacement machine for compressible media. More particularly, it relates to for a spiral displacement machine having a lubricant system.
2. Background of the Related Art
Spiral displacement machines forming compressors are known, for example from DE-C- 26 03 462. Such compressors provide an almost pulsation-free delivery of, for example, a gaseous working fluid consisting of air or an air-fuel mixture and therefore could advantageously be used, i.a., for supercharging internal combustion engines. During the operation of such a compressor several approximately crescent-shaped working spaces are enclosed along the displacement chamber between the spiral-shaped displacement body and the two peripheral walls of the displacement chamber. The working spaces move from the intake through the displacement chamber to an output, while their volume is continuously reduced and the pressure of the working fluid is consequently increased.
A machine of this type is also known from DE-A-3 313 000. Because two eccentric arrangements, spaced from one another, are provided, one of which can be driven by a drive shaft, a statically determined bearing results, which guarantees a forcible oscillatory guiding of the rotor except at the top and bottom dead centers of oscillation. To achieve a precise guiding at the dead center positions of the rotor, a guide shaft of the second eccentric arrangement, supported in the housing, is positively connected to the drive shaft by e.g., a synchronous belt drive. Several means are known for flexibly accommodating any optional differences in spacing between the delivery chamber and the displacement body.
A precise movement of a displacement body according to the spiral principle is achieved by a translatory circular motion, i.e., oscillation, by double crank drive, as is known, for example, from DE-A-3 230 979 and in which one crank drives and the second crank guides. To be able to equalize the differences in length between the two points of application of the drive arrangement and guide arrangement, this known solution provides a transfer element that is longitudinally slidable, namely, in the direction of the connecting line of the points of application. This transfer element consists of a holding element adjustably held in the guide arrangement of the rotor. The holding element can be a slide ring which can slide in a parallel guide. The parallel guide comprises one of the two bearings of the guide arrangement, by which thus an optional equalizing of the expansion differences can take place.
Another solution for this problem is described in DE-A-3 107 231. To avoid inadmissibly high stresses, which can occur by buildup of tolerances during production or by different heat expansions between the two points of application on the rotating rotor, a bearing arrangement with an elastic bed is provided on at least one of the points of application, preferably on the point of application of the guide device. This elastic bed can be formed, for example, by a rubber ring, which sits between the bearing outside race and the bearing eye.
In all known spiral compressors, in which for translatory guiding of the rotor a guide shaft running at a synchronous angle with the drive shaft is provided, the bearing of the two shafts takes place by roller bearings. This can be especially clearly seen in the displacement machine according to DE-A-3 141 525 in which the drive shaft is mounted in the housing in two ball bearings and an eccentric collar is placed on the drive shaft by a roller bearing, while the guide shaft is mounted in the housing by two ball bearings and the eccentric pin of the guide shaft in the rotor disk by a needle bearing. In this case, the needle bearing in the rotor disk is generally lubricated with grease (DE-A-3 638 470), while the highly stressed eccentric bearing of the drive shaft is lubricated with oil (DE-A-3 320 086).
It is known from DE-C-3 119 542, in an arrangement for the bearing of an eccentric drivable rotor, to design the bearings for a disk rotatably mounted in a stationary housing and for the driver connected with it, as slide bearings. But the basic idea of this design, in the use of the spiral machine in the engine drive, is that if the rotor is exposed to very hot gases, the complete bearing of the eccentric device is shifted onto the stationary housing where a sealing from aggressive hot gases as well as sufficient cooling are possible. In this known arrangement only the drive eccentric arrangement, but not the guide eccentric arrangement, is provided with the slide bearing.